MUNICH -- Prosecutors in Munich said they have widened an investigation at Audi to examine the company's sales in Germany and elsewhere in Europe after the federal government accused the Volkswagen Group division of cheating on emissions tests in its home market.

Audi on Thursday recalled around 24,000 A8 and A7 models in Europe, 14,000 of which were sold in Germany, to update transmission software, which it said was causing nitrogen oxide (NOx) emissions to exceed EU limits.

Munich prosecutors have been investigating Audi on suspicion of fraud and criminal advertising in the United States where parent VW Group's emissions scandal broke in September 2015. They have expanded the inquiry to include vehicle sales in the brand's home region, a spokesman for prosecutors said.

Audi said Thursday that it would continue to fully cooperate with authorities and Germany's KBA motor vehicle authority, which the carmaker had notified about the latest emissions irregularities.

The affected Audi models with so-called Euro-5 emission standards, and built between 2009 and 2013, emit about twice the legal NOx limits when the steering wheel is turned more than 15 degrees, the German transport ministry said.

Prosecutors said the suspicion in the Audi investigation still centered on fraud, adding they have not yet received updated information from the KBA on the situation in Germany.

Their investigation came to a head in March when prosecutors searched Audi's headquarters in Ingolstadt in connection with the emissions scandal, as well as a second German plant and subsequently even the U.S. law firm Day Jones that VW Group had hired to clear up its diesel emissions-cheating scandal.

The fresh findings on Audi's top models are a blow to a company that is VW Group's biggest profit contributor and therefore a vital component to absorb the hit from the diesel-emissions scandal that has cost the manufacturer 22.6 billion euros ($25.4 billion) so far.

From the roughly 11 million diesel cars affected worldwide across the VW Group, Audi has accounted for about 2.1 million vehicles until now.